asked
I have a75/15 mppt with 90 watt solar panel and 2 12 volt lead acid batteries I have 19.67 volts at end of wires, but as soon as I connect them to mppt it shows more or less the same volts as the battery volts. What can I do
Add more panels or get a bigger voltage panel. There is nothing you can do if the Voltage Open Circuit (voltage without load) is not much higher than the battery voltage.
As soon as those panels are loaded the voltage will drop and the mppt will switch to off again.
https://www.youtube.com/watch?v=uTMVmW7GTus
https://www.youtube.com/watch?v=EVAvRs32TiE
Your battery voltage will be above 12v, the PV voltage is barely 5v above the battery voltage.
But that is 19v no load., so 19v 0amps. When the panels are loaded to try charge with amps, their voltage is dropping and the mppt is switching off.
Try series connect more panels and see if you can increase the Voltage Open Circuit. Please see the example below for connection ideas.
